According to a report by the Financial Times, some banks have begun monitoring traders’ performance against the number of times they use internal communications systems. The purpose of this monitoring is to identify whether traders are covertly contacting clients and illegally profiting from doing so, it said. Banks are also monitoring mobile phone use and using data to log the number of times traders take a break to smoke outside to identify suspicions patterns that hint at insider trading, the report said.

Financial services litigation and compliance expert Michael Ruck of Pinsent Masons, the law firm behind Out-Law.com, said that it is understandable that banks would turn to big data for staff surveillance because of the penalties they could face for insider trading. However, he said that the scope of surveillance needs to be tempered by consideration of legal and employee relations issues.